1. Field of the Invention
The present invention relates to supports for correcting abnormal dentition which can serve as supporting points for relocating or moving an improperly positioned tooth in orthodontic treatment.
2. Description of the Related Art
Orthodontic treatment for correcting irregularities in teeth arrangement, such as crowded teeth, reversed occlusion or inclination of front teeth to the labial side, is getting popular.
One of the most popular methods of orthodontic treatment includes the steps of fixing brackets to surfaces of individual teeth with an adhesive, for instance, passing an arch wire through the brackets, and relatively moving the individual teeth by applying external forces (which may be hereinafter referred to as correcting forces in this Specification), such as pushing, pulling or twisting forces, to the teeth by use of a restoring force caused by the elasticity of the arch wire, so that the teeth would be adjusted to take proper positions and directions to achieve as a whole a correct dentition. This method may be hereinafter referred to as relative movement orthodontic treatment.
In such relative movement orthodontic treatment, molars, especially the first molars, which are large and difficult to move, are used as sources of anchorage in most cases. It is, however, too much to say that the molars do not move at all. In fact, the molars which have been located at correct positions could be displaced in certain cases as a result of orthodontic treatment. On the contrary, there are cases where it is desired to positively move a molar. In such cases, the orthodontic treatment involves complicated movements and techniques for correcting the arrangement of the teeth which would require an extended period of time, imposing a heavy burden on a patient.
Another method of relative movement orthodontic treatment is to use extraoral anchorage in which the head of a patient is used as a source of anchorage, for instance. An extraoral anchorage orthodontic appliance, however, imposes considerable mental pain and stress on the patient because wearing the extraoral anchorage appliance greatly affects his or her daily life.
In addition, the aforementioned method of relative movement orthodontic treatment is not suited for correcting the position of a single tooth.
To overcome the foregoing problems, U.S. Pat. No. 5,921,774 (Japanese Unexamined Patent Publication No. 10-99347) proposes orthodontic treatment using an orthodontic supporting structure.
This orthodontic supporting structure comprises an implant portion (implant unit) to be implanted in a desired site in a jaw bone and an exposed portion (connecting unit) which can be attached to a head of the implant portion. The implant portion measures 2 mm at the maximum in the diameter of its horizontal cross section and the exposed portion includes an arm having a hook (fastening part) which would extend into the oral cavity.
With the support implanted in the jaw bone, one end of a resin chain or a metallic coil spring or the like is connected to the fastening part of the support and the other end is connected to a bracket or a lingual button, for instance, which is fixed to a tooth in order to apply a correcting force, such as a pushing or pulling force, to the tooth.
Since the arm of the orthodontic supporting structure allows the fastening part serving as a supporting point for the correcting force to be located away from the implant site in the jaw bone, it is possible to situate the fastening part at a position most preferable for applying the correcting force even when the support is implanted where it does not interfere with nerves or tooth roots.
The orthodontic supporting structure of the aforementioned Publication is suited for correcting the position of a single tooth because it can apply the correcting force directly to each individual tooth. Furthermore, this orthodontic supporting structure makes it possible to exert the correcting force from a supporting point most suited to the tooth to be corrected without adversely affecting correctly positioned teeth. Thus, the support can correct the improperly positioned tooth without the need for complicated orthodontic treatment and reduce the time period required for the treatment.
An orthodontic supporting structure of the present invention comprises an implant unit which is implanted in a desired site in a jaw bone and a connecting unit attachable to an upper portion of the implant unit, the connecting unit including an arm part having a fastening portion which extends in an oral cavity and an engaging part having an opening at one end which is formed to allow the connecting unit to detachably fit on the implant unit in a direction intersecting a longitudinal axis of the implant unit.
These and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description along with the accompanying drawings.